One commercially available sandal includes a flexible sole, to which are attached a pair of flexible straps extending over a forward part of a foot of a wearer and an elastic strap extending over the heel of the wearer. The heel strap extends from the forward part of the sole, in the vicinity of the straps that extend over the forward part of the foot, around the heel of the wearer. In one arrangement, the sole has a laminated ethyl vinyl acetate (EVA) construction. The straps have been manually attached to the sole between upper and intermediate laminated layers so they extend through elongated slits in the upper layer. The manual operations tend to increase the cost of producing the sandals.
London et al., U.S. Pat. No. 3,474,477 discloses a method of and apparatus for making sandals and other open top footwear. A prefabricated upper including a sole piece, to which are adhered toe and heel straps, is secured to a last having flexible lower corners. The last includes a nail or the like for piercing the sole piece, to assist in holding the upper in situ on the last. The last with the upper secured thereto fits into a mold cavity formed by a sole plate and a pair of ring members. The top of the cavity is defined by a pair of relatively sharp sealing lips that engage straps on the upper, and flexible material on the last lower edges.
The relatively sharp lips which bear against the sides of the straps would appear to have a tendency slightly to damage the straps. In addition, the sharp lips have a tendency to wear so that the seal formed thereby would appear quickly to deteriorate with use. In addition, the need for flexible material in the last has a tendency to increase the cost of the mold. The flexible material in the last is incapable of withstanding the repeated high temperature cycling associated with injection molding operations. The molded sole has a tendency to adhere to the flexible material on the last edges.
It is, accordingly, an object of the present invention to provide a new and improved method of and apparatus for making footwear having injection molded soles.
Another object of the invention is to provide a new and improved apparatus for and method of making injection molded footwear wherein the number of manual operations is reduced relative to the prior art and wherein relatively inexpensive and long lasting molds are employed.
A further object of the invention is to provide a new and improved apparatus for and method of making sandals including a toe strap and a heel strap connected to the sole in the vicinity of the toe strap.
A further object of the invention is to provide a new and improved, relatively inexpensive sandal including toe and heel straps made of flexible material.